Effects of Hydraulic Detention Time, Water Depth, and Duration of Operation on Nitrogen and Phosphorus Removal in a Flow-Through Duckweed Bioremediation System

Al-Ahmady, Kossay K.; Stevens, Kenneth N.; Atkinson, Sam

doi:10.1061/(asce)ee.1943-7870.0000627

Cited by 9 publications

(3 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, in cold climates, wastewater is applied at very low hydraulic loading rates [4] and low organic loading rates of less than 60 kgBOD 5 /ha/d [5]. Waste stabilization ponds are commonly used for treatment of wastewater from domestic, industrial and agricultural sources [6]- [9] with an objective of reduction of organic matter [2] [10] [12], pathogenic organisms [13]- [15] and nutrients particularly nitrogen [3] [6] [16].…”

Section: Introductionmentioning

confidence: 99%

Dynamics of Nitrogen Transformation and Removal in a Pilot High Rate Pond

Mayo¹,

Hanai²

2014

JWARP

View full text Add to dashboard Cite

The transformation and removal of nitrogen was studied in a pilot high rate pond with a surface area of 10.2 m 2 and water depth of 60 cm. The pilot unit received wastewater from an existing field scale primary facultative pond at the University of Dar es Salaam. Wastewater samples were collected from the influent and effluent of high rate pond and were analyzed for physical-chemical parameters in the laboratory and in situ. An appropriate model complexity was selected, from which a conceptual model was then developed to model various processes in the system using STELLA 6.0.1 software. The study demonstrated that dominant nitrogen transformation processes in HRP were nitrification and denitrification, which transformed 0.95 and 0.87 gN/m 2 •d, respectively. These were followed by mineralization (0.37 gN/m 2 •d), ammonia uptake by microorganisms (0.34 gN/m 2 •d), volatilization (0.30 gN/m 2 •d), sedimentation (0.24 gN/m 2 •d), and regeneration (0.15 gN/m 2 •d). Uptake of nitrate was not observed because of microorganisms preference for ammonia, which was abundant in the pond. The major nitrogen transformation mechanisms in high rate pond were denitrification, net sedimentation and volatilization, which accounted for 69.1%, 7.1% and 23.8% of the total permanent removal mechanisms of nitrogen in High Rate Pond.

show abstract

Section: Introductionmentioning

confidence: 99%

Dynamics of Nitrogen Transformation and Removal in a Pilot High Rate Pond

Mayo¹,

Hanai²

2014

JWARP

View full text Add to dashboard Cite

show abstract

“…The model developed for this study provides a validated tool that may be used to help inform sustainable management strategies in restored and natural streams with abundant duckweed biomass. Harvesting of duckweed biomass is common in wastewater and wetland treatment systems [27,[29][30][31]34,36,40], and has indicated that periodic, planned duckweed harvest could improve the overall N uptake by reducing the biomass periodically to allow for rapid regrowth of duckweed mats. This would also permanently remove the assimilated N from the stream, reducing the loss of living organic matter to receiving waterbodies during storm events that cause catastrophic scour.…”

Section: Broader Implicationsmentioning

confidence: 99%

“…Much of the nutrient removal research regarding duckweed has focused on wastewater ponds, stormwater detention basins, and constructed wetlands [27][28][29][30][31][32][33]. Results from these landscapes have shown that duckweed grows rapidly in N-rich environments and is highly efficient at removing N over long-periods of time, with active life-spans of mats exceeding 25 days [34]. As a result of rapid growth rates, duckweed is often harvested to optimize nutrient removal [27].…”

Section: Introductionmentioning

confidence: 99%

Reach-Scale Model of Aquatic Vegetation Quantifies N Fate in a Bedrock-Controlled Karst Agroecosystem Stream

Bunnell

Ford

Fogle

et al. 2020

Water

View full text Add to dashboard Cite

In-stream fate of nutrients in karst agroecosystems remains poorly understood. The significance of these streams is recognized given spring/surface water confluences have been identified as hotspots for biogeochemical transformations. In slow-moving streams high in dissolved inorganic nutrients, benthic and floating aquatic macrophytes are recognized to proliferate and drastically impact nutrient fate; however, models that quantify coupled interactions between these pools are limited. We present a reach-scale modeling framework of nitrogen dynamics in bedrock-controlled streams that accounts for coupled interactions between hydrology, hydraulics, and biotic dynamics and is validated using a multi-year, biweekly dataset. A fluvial N budget with uncertainty was developed to quantify transformation dynamics for the dissolved inorganic nitrogen (DIN) pool using a GLUE-like modeling framework, and scenario analyses were run to test for model function over variable environmental conditions. Results from a 10,000 run uncertainty analysis yielded 195 acceptable parameter sets for the calibration period (2000–2002), 47 of which were acceptable for the validation period (2003) (Nash-Sutcliffe Efficiency (NSE) > 0.65; percent bias (PBIAS) < ±15), with significantly different posterior parameter spaces for parameters including denitrification coefficients and duckweed growth factors. The posterior solution space yielded model runs with differing biomass controls on DIN, including both algae and duckweed, but suggested duckweed denitrifies at a rate that would place the bedrock agroecosystem stream on the high-end of rates reported in the literature, contradicting the existing paradigm about bedrock streams. We discuss broader implications for watershed-scale water quality modeling and implementation strategies of management practices for karst agroecosystems, particularly with respect to stream restoration.

show abstract